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Changes in hydrological interactions of the Yangtze River and the Poyang Lake in China during 1957-2008

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Interaction of the Yangtze River and the Poyang Lake strongly affects the Poyang Lake water resources and flood and drought potentials in the lake basin. This interaction and its variation are examined in this study for the period 1957-2008. In addition, changes in the relationship between the Yangtze River and Poyang Lake after the operation of the Three-Gorge Dam (TGD) are evaluated using the TGD operation data available for 2004-2006. Major findings are shown as follows. 1) At interannual to decadal timescales the variation in the Poyang Lake water level is primarily determined by fluctuations of the climate and the inflow from the five major tributaries in the lake basin. By influencing the lake level these fluctuations also affect the lake-river interaction. 2) At the seasonal timescale, the Poyang Lake has the largest outflow to the Yangtze River and exerts a strong pressure on the mainstream during April-June, when the lake receives annual peak inflow from its tributaries. The Yangtze River's blocking and/or reversed flow to the Poyang Lake are the strongest during July-September. 3) The operation of the TGD has changed little in terms of seasonal variations of these lake and river forcings. In most of the seasons, the influence of the TGD has resulted in less than 10% of the variation in the Yangtze River flow. However, by damming or releasing water, the TGD can result in seasonal changes in the Yangtze River flow and river-lake interactions. These subtle effects from the TGD operation are quantified and compared to the climate effect on the river-lake interactions. These comparisons show enhancement in some seasons while weakening in the other seasons of the climate effect on river-lake interactions and flood or drought potential in the lake basin by the TGD operation.
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地理学报
ACTA GEOGRAPHICA SINICA
66 5
2011 5
Vol.66, No.5
May, 2011
收稿日期:2010-11-23; 修订日期:2011-03-21
基金项目:中国科学院知识创新工程重要方向项目 (KZCX1-YW-08-01; KZCX2-YW-337); 中国科学院南京地理与湖泊
研究所科学基金(NIGLAS2010XK02); (40871026; 41001017); 美国农业部研究项目
(NEB40-040) [Foundation: The Knowledge Innovation Projects of the Chinese Academy of Sciences, No.
KZCX1-YW-08-01; No.KZCX2-YW-337; Science Foundation of Nanjing Institute of Geography and Limnology,
CAS, No.NIGLAS2010XK02; National Natural Science Foundation of China, No.40871026; No.41001017; US-
DA Research Project, NEB40-040]
作者简介郭华 E-mail: hguo@niglas.ac.cn
通讯作者张奇 (1966-), ,研究员,主要从事湖泊流域径流量和物质通量对气候变化和人类活动的响应机制研究。
E-mail: qzhang@niglas.ac.cn
609-618
50 年来长江与鄱阳湖水文相互作用的变化
郭 华
1
, HU Qi
2
,张 奇
1
(1. 中国科学院南京地理与湖泊研究所,湖泊与环境国家重点试验室,南京 210008;
2. School of Natural Resources, and Department of Earth and Atmospheric Sciences,
University of Nebraska-Lincoln, Lincoln, NE68583-0987, 美国)
摘要:通过分析 1957-2008 年长江与鄱阳湖相互作用的基本特征及其与长江中游、鄱阳湖流域的
径流量和 气候变化的关 系,并用 2004-2006 年三峡水库蓄水、放水量的数据,定量地计算和比较
了三峡水库运行和区域气候变化对长江与鄱阳湖相互作用的影响程度得出如下主要结论1)
从年际、代际尺度上来看,鄱阳湖流域的气候变化和五河入湖流量是鄱阳湖水位和水量变化
的主要因素,同时也在很大程度上决定了长江与鄱阳湖相互作用关系及其强弱变化。2) 长江与
鄱阳湖的相互作用强度是此消彼长的关系。从季节来看,鄱阳湖对长江的较强作用主要在 4-6
月,而长江对 鄱阳湖的较强作 用主要发生在 7-9 月。3) 三峡水库运行并没有改变长江与鄱阳湖
作用的基本特征,在多数季节三峡水库的影响不足以解释长江径流量变化的 10%但是水库在不
同季节的蓄水或放水在一定程度上影响了江湖作用的季节变化和鄱阳湖流域的旱涝机率。4-6
月的放水加强了长江作用,由于此时正值鄱阳湖流域的雨季,增强的长江作用在湿润气候的环
境下可能增加初夏鄱阳湖流域的洪涝的概率;7-9 月的少量蓄水则减弱长江对鄱阳湖的作用,
低了湖区洪涝的概率;10 月份三峡水库的大量蓄水可能增加鄱阳湖流域的旱季干旱发生率。
关键词:长江;鄱阳湖;江湖作用;气候;三峡工程运行
长江与沿江湖泊的相互作用一直是人们关注的问题。研究江湖相互作用对于湖泊流域
水循环、江湖洪旱灾害发生机制、控制入湖水和出湖水的水量和水质,及湖泊水生态等都
至关重要[1-2]。但是由于涉及复杂的江湖动力学机制以及气候变化和人类活动等诸多影响因
素,这方面的研究尚未深入开展。
在我国长江流域,鄱阳湖是重要通江湖泊之一,与长江进行着复杂的水文和水动力交
作用。认识长江与鄱阳湖相互作用及江湖关系的变化对保护鄱阳湖水资源和区域生态环境
等具有重要理论价值。Hu [3]对长江与鄱阳湖相互作用的研究首次定量化地描述了长江对
鄱阳湖水量变化的影响。他们对于 1960-2003 年江湖作用的初步分析结果表明:鄱阳湖流域
内五河水系的来水量是影响鄱阳湖水位以及造成洪水的主要原因,长江的顶托和倒灌作用
是次要的;五河对鄱阳湖作用较强的时期是 1970s 1990s其 中 1990s 是五河水系对鄱阳湖
作用最强的时期,同时也是长江对鄱阳湖作用最弱的时期。造成这种江湖作用变化的主要
原因是鄱阳 湖流域及长江流域 的春夏季降水的变化 :例如 1990s由于华东主要雨带的分布
异常同时影响 长江中上游和鄱阳湖流 域,增大 了鄱阳湖流域 7-8 月降雨量,使湖水位在前三
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个月高水位基础上进一步上[3]加上此季节长江流量洪峰的到来,使鄱阳湖区发生严重洪
涝灾害[3-4]
2003 年之后三峡工程开始调度运行,它对长江年径流量的影响尚不明显[4-5]但是增
了人为因素对长江流量季节变化的影响[6-9]也因此影响江湖相互作用以及鄱阳湖水位、水量
的季节变化。三峡水库运行后,前一年 9-10 月份蓄水,翌年 5-6 月上旬下泄,这种运行方式
可能人为地加5-6 月长江流量,提前于 5-6 月造成江对湖的顶托作用,升高湖水位[10]
9-10 月的蓄水则减少了枯水期长江流量,增大了鄱阳湖向江的汇流降低湖水位。Dai [11]
研究了 2006 年三峡运行 对长江流量的影响 。结果表明,2006 920 日至 10 27 日长
江大通站流量相 对于 2005 年同期减少的 54%中,45%归因于 2006 年的干旱,9%归因于三
峡运行。此外,输沙量的明显减少[5-6, 12-14]也反映了三峡运行使长江径流量有所改变。三峡工
程运行后的两年 使长江输沙量减少了 31%[13]。由于输沙量与径流量呈正比关系[5-6, 12-14]输沙
量的减少指出三峡运行后长江径流量的减少。三峡工程运行后长江流量的变化势必造成长
江与鄱阳湖相互作用的变化。
定量研究长江与鄱阳湖的水文相互作用和三峡运行的影响,及由此造成的鄱阳湖水
位、水资源的变化,对于鄱阳湖区域生态管理和经济发展具有重要意义。
在前期研究[3]的基础上,本文首先分析了过去 50 多年 (1957-2008 )长江与鄱阳湖径流
量变化,进一 步研究长江与鄱阳湖相 互作用关系和变化,并 通过分析 2004-2006 年长江与鄱
阳湖相互作用变化的主要原因来区分气候变化和三峡运行各自对江湖作用的影响程度。
1数据和方法
本文采用的水文数据是 1957-2008 年汉口、湖口 (1) 及鄱阳湖五河水系出口站的日流
量数据,以及用于计算三峡水库月放水和蓄水量的 2004-2006 年入库和出库日流量数据。以
上水文数据来自长江水利委员会以及江西省水文局,并由他们进行了数据质量控制。降水
量计算采用中国气象局国家气象信息中心气候资料室提供的 1957-2008 年日降水量数据,
中长江中游 74 个站点 (1)。该降水数据集 由 Feng [15]做了严格的数据质量控制。文中提
到的“距平”是指相对于 1957-2008 年平均值的年变化量。相关性分析检验采用 t-test 方法。
长江对鄱阳湖 的作用延用 Hu [3]的方法来计算。同时根据 Hu [3]的研究方法,我们用
1长江中游雨量站及主要水文站分布图
Fig. 1 Geographical distribution of precipitation and hydrological stations in the middle Yangtze River Basin
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5 等:50 年来长江与鄱阳湖水文相互作用的变化
五河入湖总流量和湖口 站流量定义了鄱阳湖对长江的作用,即当二者 流量均大于 7000 m3s-1
时,鄱阳湖对长江产生较强的作用。该作用的物理意义在于五河水持续、大量地汇入鄱
湖,注入长江,形成湖对江的强力作用。
根据以往的研究,4-6 月是鄱阳湖流域降水量最大、鄱阳湖流域的五河 (修水、赣江、
河、信江和饶河)入湖总汇流量增速最大的季节[16]7-9 月是长江中上游降水量较大且长江干
流径流量最大的季节[17]10 月到来年的 3月为低水或枯水期。2003 年三峡水库蓄水运行后,
水库在 10 月份的大量蓄水 增加了枯水期长江和鄱 阳湖的水量变 化,此我们分 别研究 4-6
月、7-9 月和 10 这三个时段的长江流量变化和长江与鄱阳湖相互作用的变化。并通过
析这些作用在三峡运行前后的变化来定量阐述三峡的影响。
研究三峡水库运行对长江和江湖作用的影响的一个理想的方法是滤除气候的影响。在
实际计算中通常可用选择相似气候年份再平均的方(composite analysis)。但由于三峡运
行到现在仅有 7年,而且近些年气候变化剧烈,很难找到降水相似的气候年份。气候差异较
大的年份往往难以去除气候的影响,所以我们通过三峡蓄/放水量、长江中游相对于平水年
的流量变化来分别计算气候变化和三峡工程运行的这 7年里对长江流量和长江与鄱阳湖水
文相互作用的影响程度。在研究三峡运行之后 (2004-2008 )三个季节时段 (4-6 月、7-9
10 )长江中游流量变化及其与江湖作用变化的关系时,们用百分位数 (percentile)
方法确定三 个季节时段的平水年,具 体方法是:首先计算 1957-2002 年每年该季节平均径流
量的百分 位数,然后选出百 分位数为第 50±5 的年份,它们的平均径流量即为该季节的平水
年的径流量。
2长江与鄱阳湖相互作用特征及其变化
长江与鄱阳湖的相互作用表现在两个方面,一方面是长江对鄱阳湖的作用 (以下简称长
江作用)包括顶托和倒灌作用。较强的长江作用可使鄱阳湖水位升高;另一方面是鄱阳湖
对长江的作用 (以下简称鄱阳湖作用)当鄱阳湖向长江大流量地持续汇流,鄱阳湖作用增
强,造成长江下游流量增加。
50 年的时间尺度里长江作用的产生主要有两个原因:是由于长江中上游降水量
的增加,使长江流量增大,水位升高,对鄱阳湖产生顶托或倒灌作用;二是由于鄱阳湖流域五
河水系上游来水减少,鄱阳湖干旱,湖水位降低,间接使长江水位升高,长江作用增强。
鄱阳湖作用的产生也有两个原因:一是鄱阳湖流域降水增加,五河水系流量增大汇入
鄱阳湖,使其水位升高,增加向长江的梯度力,从而产生较大流量汇入长江;二是长江中上游
流量减少,长江中游干流水位下降,使鄱阳湖水位相对升高,产生较大流量汇入长江。
长江作用和鄱阳湖作用影响江—湖的水量交换强度。由于长江中上游流域和鄱阳湖流
域有着不同的降水季节变化特征,长江作用和鄱阳湖作用随季节变化且相互影响致江、
湖的水位和流量的季节变化和年变化。当两者都很强的时候,鄱阳湖的洪水概率增大;当两
者都很弱的时候,鄱阳湖的干旱增强。这些江湖作用的季节变化在三峡水库的运行之后变
得更加复杂。
2.1 长江与鄱阳湖作用的年际和年代际变化特征
从近 50 (1957-2008 )长江对鄱阳湖的作用强度来看,整体呈减弱趋势,但存在较为
明显的年代际波(2)。图 2a 中实心圆标注长江对鄱阳湖作用较强的年份,空心圆标注
长江对鄱阳湖作用较弱的年份,由此图可知:长江对鄱阳湖作用有两个的较强时期:1950s
1960s 末和 1980s 初至 1990s 初。这两个时期长江流量较大而鄱阳湖地区较为干旱,五河
入湖流量较少 (2b)相对增强了长江作用。图 2a 也指出长江对鄱阳湖作用较弱的两个时
期:1960s 末至 1970s 末和 1990s 初 至 2000s 初。这两个时期长江流量较小,五河入湖流量较
611
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地 理 学 报
(2b 中阴影部分)
湖对长江作用较强这些
果指出长江与鄱阳的相
作用强度在年代际度上
一个此消彼长的关系,而这个
关系与长江中上游鄱阳
流域的降水的年代变化
切相 关。此 外,如 图 2所示,
三 峡 水 库 初 期 运 行 后
(2003-2008 )江 湖 相 互 作
用频率变化基本保原有
变化规律,表示三峡水库运行
对江湖作用的影响对于
候的影响来说并不明显。
2.2 长江与鄱阳湖作用的
季节变化特征
1957-2008 年的长江
作用和鄱阳湖作用的日累
次数季节特征来看 (3)
江作用 主要发生在 7-9 月,
鄱阳湖作用主要在 4-6 月 。
1957-2008 4-6 月鄱阳湖作
用总频数共为 1117
江 作 用 频 数 仅 为 66 次。与
4-6 月的频率形式相反,7-9
江作 用总1030 次,
226
次。10 -3 月的长江和鄱阳
湖的作用都明显减弱,但是相
言,10
12-3
的鄱阳湖作用强于长江作用。
以上江湖作用特征与该
地区年降水分有密切关
系,而年降水分布规律又与东
亚夏季季风的迁移规律密切相关。根据夏季季风的季节进退规律[18-19]5-6 月季风锋面在长
江以南,降水集中在长江以南,影响鄱阳湖流域,流域内五河入湖流量迅速增加,达到年最大
值。此期间鄱阳湖向长江的汇流作用最大,增强鄱阳湖作用。7-8 月季风锋面移到长江
北,长江中上游降水量增大,汇流量增大,而使长江作用增强。9月之后季风锋面又返回
到长江以南,但是强度明显减弱。
3长江与鄱阳湖的流量变化与江湖作用的关系
长江与鄱阳湖流量的变化主要受区域气候的影响[3, 14, 16-17]而区域气候又是较大背景下
2 1957-2008 年每年长江对鄱阳湖作用较强的天数(a)
和五河入湖流量的年际变化(b)
Fig. 2 (a) Variation in the number of days of a year when the Yangtze River had
strong effects on the Poyang Lakeand (b) variation in the total discharge
from the Poyang Lake basin to the lake during 1957-2008
3 1957-2008 年长江与鄱阳湖作用的频率分布
Fig. 3 Frequency distribution of the Yangtze River effect (dark shading) and
the Poyang Lake effect (light shading) averaged for the period 1957-2008
612
5 等:50 年来长江与鄱阳湖水文相互作用的变化
气候变化的缩影。长江中游降水量与径流量的相关性较好,以长江作用较强的季节 7-9 月为
例,二者的 相关系数为 0.6通过95%的置信度检验。长江中游降水量的变化在很大程度
上影响着其径流量变化,预测长江中游降水对预测长江对鄱阳湖的作用有直接的意义。
4a-b 分别是长江作用较强和鄱阳湖作用较强的年份长江流域的降水距平分布,
的是通过进一步比较长江中游和鄱阳湖流域的区域降水特征 (与周边和其它区域的不同)
来分析江湖作用发生变化时长江中游和鄱阳湖流域降水量的相对变化 (4)以此来描述区
域气候变化在影响江湖相互作用中的重要性。
在长江作用较强的两个时期,1950s 末至 1960s 末和 1980s 1990s (2a)鄱阳湖
流域 7-9 月降水量偏少 (4a)五河入湖流量偏少 (2b5b)。同时期,长江中游降水偏
(5b [14] 有相同的结)。长江干流汉口站的同期平均流量高于 50 年平均流量 (
5a)。因此这两个时期的长江作用增强是鄱阳湖流域降水减少导致五河入湖流量减少,以及
长江中游降水增加导致长江流量增大的综合结果。
在鄱阳湖作用较强的时期,1960s 末至 1970s 末和 1990s 初至 2000s 初,鄱阳湖流域 7-9
的降水量高于 1957-2008 的平均 (4b)五河入湖的汇流较大 (2b5b)导致鄱阳湖流
域水位升高。而同期长江中游的降水偏少 (4b)汉口站同期的平均流量低于 50 年平均流
(5a)长江对鄱阳湖作用较弱。此时期鄱阳湖对长江作用很强。
从上述长江中游与 鄱阳湖流域的 50 年径流量变化特征与江湖作用的关系来看,江湖作
用强弱的变化是鄱阳湖流域流量和长江流量相对变化的反映,如此变化的主要原因是鄱阳
湖流域降水量与长江中上游的相反的分布格局所造成。
分析长江中游流量、鄱阳湖流域汇流量变化及其与江湖作用的关系 (2)我们认为从
4 a) 长江作用强的年份的 7-9 月降水量距平; b) 鄱阳湖作用强的年份的 7-9 月降水量距平
(1957-2008 年降水量的百分比)
Fig. 4 Summer precipitation anomalies for a) the years with strong Yangtze River effect, and b) the years with strong
Poyang Lake effect (percent of the 1957-2008 annual mean precipitation)
613
66
地 理 学 报
年代际尺度上来看,
阳湖流域的五河入湖流
量是鄱阳湖水位和水量
变化的主要因素,同时
也在很大程度上决定了
长江与鄱阳湖相互作用
关系及其强弱。
但是当鄱阳湖流域
较干的时候,长江中游
的流量变化对江湖作用
的 影 响 就 变 得 比 较 重
要。特别2003 年后,
鄱阳湖流域连年干旱,
三峡水库运行通过调节
长江中下游季节流量,
进而影响到长江与鄱阳
湖的相互作用的强度和
频率。
4 2003 年后江湖作用的季节变化以及气候和三峡水库的影响
2003 年三峡水库运行后,水库通过调节长江中下游季节流量直接影响江湖作用和鄱阳
湖的水位,这些影响叠加在气候变化的影响上使得江湖作用更加复杂。这里我们首先分
三峡水库运行后 (2004-2008 )长江中下游流量和鄱阳湖水量收支相对于历史平水年的变
化,之后进一步定量分析三峡水库和气候对这些总体变化的分别贡献。这些结果对理解三
峡水库对江湖作用的影响和预测鄱阳湖区域的旱涝变化都有重要参考价值。
如表 1所示,相 对于 1957-2008 期间的平水年 (19611963198019851991 1994 )
2004-2008 4-6 月长江中游降水量减少了 8.1%。虽然该季节是长江三峡的放水期,但汉口
站流量仍然减少了 7.3%与此同时,长江作用频率减少了 20%
鄱阳湖流域 2004-2008 4-6 月的平均降水量与平水年同期的平均降水量非常接近,
是五河入湖径流量减少了 4.8%。这与近年土地覆被变化以及湖区用水量的增加有关。比
如,1950s-1970s由于政治环境、基础建设以及农业发展的需求,鄱阳湖流域曾出现毁林种
田现象,造成严重水土流失。1980s-1990s 尽管森林覆盖率上升,但是植被单一,针叶林比例
过高,植被的年龄结构年轻化,时出于建设需要,大量砍伐林木的情况仍有发生[20]。近
来由于成熟林面积的增大以及人们对水土流失问题的重视,下垫面条件得到改善,地表径
量有所减少[21]。另外,鄱阳湖流域的人口密度的增(1970s 年代的 1千万到 2000 年的 4
千万)使用水量大幅度增加。上述因素的综合影响使在相同降水量的气候条件下五河入湖
的流量减少。五河入湖径流量减少,很大程度地导致鄱阳湖作用频率的减少较平水年减
5.4%
2004-2008 7-9 月与平水年同期的长江中游平均降水量大致相同,但汉口流量减少了
10.8%造成这种变化的重要原因 之一是 9月份三峡水库蓄水。但此变化对长江作用频率影
响不大,因为 7-9 月虽然长江对鄱阳湖作用强度有所减弱,但频数总体并未减少。同期鄱阳
湖流域降水量减少,五河入湖径流量减少了 21%使得鄱阳湖作用频率大幅度减少,变化率
-84% (1)
5 1957-2008 年长江汉口站(a)和鄱阳湖流域五河入湖(b)7-9 月流量距平
Fig. 5 Variations of anomalies of July-September discharge of the Yangtze River at Hankou
station (a), and inflow from the 5 sub-river basins to the Poyang Lake (b) during 1957-2008
614
5 等:50 年来长江与鄱阳湖水文相互作用的变化
2004-2008 10 月长江中游
平均降水量减少,加之该季节三
峡水库较大幅度的蓄水,汉口站
量锐 减,20%
长江作用频率也明显减弱,减少
90% ( 此百分比与小基数有
)长江作用最弱1990s
强度还要小。同时鄱阳湖流域
降水量和五河入湖流量也分别比
平水 年减少 了 14%23%
鄱阳湖作用频率未有明显变化
(1)。在 作用 大幅
减少的情况下阳湖作用频率
一般会有所增大,但是由于五河
入湖流量也在减少种相互抵
消作用使得鄱阳湖作用频率变化
不大。
相对于 4-6 月和 7-9 而言
10 的降
(长江游和阳湖域降
分别减少 30%14%)加上 10
份的大幅度的水库蓄水使得长
江作用频率明显减少。
如前所述,长江作 用集中发生在 7-9 月,鄱阳湖作用集中在 4-6 月。三峡工程运行之后,
总的来说,4-6 月以放水为主。三峡放水造成的中游长江流量的增加可导致 4-6 月长江作用
增强,但我们的分析结果指出,2004-2008 4-6 月长江和鄱阳湖作用的频率均略低于平水年
同期的频率。7-9 月三峡少量蓄 水,减少长 江流量,2004-2008 7-9 月长江作用与平水年
的同期作用频率相同或略高 (1)鄱阳湖作用频率显著减少 (-84%见表 1)。进入 10
后,三峡水库大量蓄(为全年最大的蓄水月)长江作用频率减少幅度最大。2004-2008
10 月份长 江流量以及长 江与鄱阳湖 相互作用的变 化与三峡水 库蓄水影响相 一致,而在 4-6
月则并未表现出三峡水库放水的影响。这些看似矛盾的结果实质上指出区域气候变化对江
湖相互作用有着 重要影响。在表 1的结果中可得到这些定性的气候影响特征。比如,4-6
长江中游 2004-2008 年的平均降水量比平水年减少 40 mm造成长江流量减少。此时虽然三
峡水库放水,但不足以平衡降水量减少的影响,造成长江流量减少,对鄱阳湖的作用减弱。
为进一步定量地认识气候变化的影响,我们对 2004-2006 三年的气候和三峡水库运行在
不同季节对长江作用的影响分别进行分析(2)。可以看到 2004 4-6 长江径流变化率
-0.9%其中气候影响为-1.2%三峡水库放水使径流量增加,影响比率为 0.3%。这些结果
表明 2004-2006 年气候因素对长江径流和长江作用的变化起了主要影响,而三峡放水的影响
是次要的。
进一步的分析得到,2005 4-6 月长江径 流量增加了 5.5%气候影响比率为 4.9%三峡
放水影响比率为 0.6%2006 4-6 月相对于 2004-2005 年长江径流量变化幅度较大:径流量
减少 7.7%其中气候影响为-8.4%而三峡放水使流量增加但影响较小,影响比率为 0.7%
对于 7-9 月来说,三峡 水库少量蓄水,特别是 2006 年为使蓄水位达到 156 m9月份提前
蓄水,月平 均蓄水量达到 1245 m3/s2004-2005 年三峡对径流量的影响很小,主要是气候对
1长江中游和鄱阳湖流域年内降水量、径流量和长江与鄱阳湖
相互作用频率相对于平水年的变化
Tab. 1 Anomalies of precipitation in the middle Yangtze River and the
Poyang Lake basin, discharge at Hankou station, and the inflow from the
lake basin to the Poyang Lake, averaged over 2004-2008. The anomalies
are relative to the average flow years (shown in the third column). The last
two rows in each period show the Yangtze River forcing and the Poyang
Lake forcing change averaged for 2004-2008 from that of the average flow
years
季节 变量 平水年
 
 
变化率 
 
长江中游降水量   4     
汉口站流量 
    2   
鄱阳湖流域降水量 
 
  6   
五河流量总 
  6     
长江作用频   2     
 
鄱阳湖作用频率 
 
  2   
长江中游降水量   4     
汉口站流量 
    3   
鄱阳湖流域降水量 
 
  3   
五河流量总 
  3     
长江作用频   1     
 
鄱阳湖作用频率 
 
  0   
长江中游降水量   7     
汉口站流量 
    2   
鄱阳湖流域降水量 
 
  3   
五河流量总 
  1     
长江作用频   2     
 
鄱阳湖作用频率 
 
  0   
615
66
地 理 学 报
长江中游径流量的影响。2006 年由于 9月份的蓄
水使径流量 大约减少 了 1.1%由于气候干旱则使
径流量减少约 40.4%
10 月份三峡水库大量蓄水,对长江径流量的
影响比重有明显增加。2004 10 月径流量减少了
10.3%其中干旱气候的贡献率-8.2%三峡蓄水
贡献率为-2.1%2005 年径流量增加了 3.3%气候
影响比率为 4.6%而三峡蓄水使流量减少,影响比
率为-1.3%2006 10 月是蓄水比较大的月份,
平均蓄水量为 2749 m3/s。长江径流量相比 2004
2005 年而言,有大幅度的减少,减少了 49.2%其中
气候影响占到-38.5% 而三峡蓄水影响也比
2004-2005 年增大很多,达到-10.7%
综上所述,三峡水库初期调度运行对长江流
量的影响较小,只有在 10 月份较强蓄水时的影响较大,特别是 2006 10 月对径流量变化的
影响比率达-10.7%。 由于这些影 响,即使是 在 2006 10 月,都远比气候的影响小得多。
所以,我们可以 认为三峡水库的运行并 没有改变长江与鄱阳湖 作用的基本特征,7-9 月仍
然是长江对鄱阳湖作用较强的季节,4-6 月是鄱阳湖对长江作用较强的季节。10 月份的
大量蓄水对减少长 江流量有较显著的影响,使得 10 月份长江对鄱阳湖的作用频率有明显减
弱。
5结论与讨论
通过分析 1957-2008 年长江与鄱阳湖相互作用的基本特征及其与长江、鄱阳湖流域的径
流量变化的关系,并利用 2004-2006 年三峡水库放水、蓄水量的数据定量地计算和比较了三
峡水库运行 (蓄水/放水)和区域气候变化分别对长江与鄱阳湖相互作用的影响程度,我们得
出如下主要结论:
(1) 长江与鄱阳湖的相互作用强度是此消彼长的关系。例如:1980s 是长江 (对鄱阳
)作用最强的时期,也是鄱阳湖 (对长江的)作用最弱的时期,1990s 是长江作用最弱的
时期,也是鄱阳湖作用最强的时期。造成如此变化的主要原因是长江中上游与鄱阳湖流域
降水量的相反的分布格局。通过长江中游流量、鄱阳湖流域汇流量变化及其与江湖作用的
关系的分析,我们认为从年代际尺度上来看,鄱阳湖流域的五河入湖流量是鄱阳湖水位和
量变化的主要因素,同时也在很大程度上决定了长江与鄱阳湖相互作用关系及其强弱。
(2) 从季节来看 ,长江作用 主要发生在 7-9 月,而鄱阳湖作用集中在 4-6 月。这种相互
用的形式与东亚夏季季风的迁移规律吻合,与长江中游和鄱阳湖流域降水强度的此消彼长
的特征相对应,说明该江湖作用的基本特征主要受气候的影响。
(3) 三峡水库初期运行之后,气候变化和三峡水库调度同时影响径流量进而影响长
与鄱阳湖相互作用频率。三峡放水和蓄水的量在年尺度上是平衡的,它是通过季节性的调
节来影响主要由区域气候变化驱动的江湖作用的频率和强度。三峡水库运行对长江径流量
的影响较小,并 没有改变长江与鄱阳湖 作用的基本特征,7-9 月仍然是长江作用较强的季
节,4-6 月是鄱阳湖作用较强的季节。2004-2008 4-6 月和 7-9 月长江与鄱阳湖相互作用
频率的变化主要是长江中上游或鄱阳湖流域降水量变化所引起的长江中游径流量或五河水
系入湖径流量的变化。总的来说三峡水库的初期运行对长江中游径流量及长江与鄱阳湖相
互作用变化的影响虽然并不明显,在多数季节三峡水库的影响不足以解释径流量变化的
2 20042005 2006 年气候和三峡运行对长
江中游径流量的影响 (相对于平水年)
Tab. 2 Climate and the Three Gorge Dam effects
on the discharge variations of the middle reaches of
the Yangtze River in 2004, 2005 and 2006
 
 
径流变化
 
%) 
气候影
 
%) 
三峡影
 
 
 
    0 
 
    - 
 
 
    - 
 
    0 
 
    - 
 
 
    - 
 
    0 
 
    - 
 
 
    - 
 
616
5 等:50 年来长江与鄱阳湖水文相互作用的变化
10%但是它在湿季和旱季对江湖作用的调节改变了洪水和干旱风险。如 2006 9月较大
幅度的水库蓄水使该年 7-9 月三峡水库的影响较 2004 2005 年有所提高。10 月份,由于三
峡水库大量蓄水,长江流量的减少较为明显,使长江作用明显减弱。
三峡水库的初期运行对长江中游径流量及长江与鄱阳湖相互作用变化的影响虽然并不
明显,是在特殊年份,2006 9月底 至 10 月底气候干旱和三峡水库大量蓄水的共同作
用严重加剧了干旱的程度[11]。三 峡 56月份放水在春季较湿的特殊年份也有可能增加初夏
的洪涝的机率。另外三峡水库运行对径流量的影响可能会放大地反映在输沙量的变化上,
而输沙量的减少会加剧河岸侵蚀,并使长江三角洲逐渐退化,进而影响到三角洲海岸带生
系统[5-6, 12-14]
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Changes in Hydrological Interactions of the Yangtze River and
the Poyang Lake in China during 1957-2008
GUO Hua1, HU Qi2, ZHANG Qi1
(1. Nanjing Institute of Geography and Limnology,State Key Laboratory of Lake Science and Environment,CAS,
Nanjing 210008, China;
2. School of Natural Resources,and Department of Earth and Atmospheric Sciences,University of Nebraska-Lincoln,
Lincoln,NE 68583-0987, USA)
Abstract: Interaction of the Yangtze River and the Poyang Lake strongly affects the Poyang
Lake water resources and flood and drought potentials in the lake basin. This interaction and its
variation are examined in this study for the period 1957-2008. In addition, changes in the
relationship between the Yangtze River and Poyang Lake after the operation of the Three-Gorge
Dam (TGD) are evaluated using the TGD operation data available for 2004-2006. Major
findings are shown as follows. 1) At interannual to decadal timescales the variation in the
Poyang Lake water level is primarily determined by fluctuations of the climate and the inflow
from the five major tributaries in the lake basin. By influencing the lake level these fluctuations
also affect the lake-river interaction. 2) At the seasonal timescale, the Poyang Lake has the
largest outflow to the Yangtze River and exerts a strong pressure on the mainstream during
April-June, when the lake receives annual peak inflow from its tributaries. The Yangtze River's
blocking and/or reversed flow to the Poyang Lake are the strongest during July-September. 3)
The operation of the TGD has changed little in terms of seasonal variations of these lake and
river forcings. In most of the seasons, the influence of the TGD has resulted in less than 10% of
the variation in the Yangtze River flow. However, by damming or releasing water, the TGD can
result in seasonal changes in the Yangtze River flow and river-lake interactions. These subtle
effects from the TGD operation are quantified and compared to the climate effect on the
river-lake interactions. These comparisons show enhancement in some seasons while weakening
in the other seasons of the climate effect on river-lake interactions and flood or drought potential
in the lake basin by the TGD operation.
Key words: Yangtze River; Poyang Lake; river-lake interactions; climate; the Three-Gorge Dam
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... The lake's floodplains are the most extensive in the Yangtze River basin [8]. The complex river-lake interactions between Poyang Lake and the Yangtze River were extensively investigated [26][27][28][29][30][31][32]. Human activities are the major factor for the decrease in discharges of the Yangtze River in the 2000s [33]. ...
... It is expected that the hydrodynamic fields, inundation extent, lake area and storage, and lake-floodplain interactions may be disturbed or altered throughout the whole system [53][54][55][56][57], due to climate change and human activities [54,[58][59][60]. Several studies were carried out to investigate the interactions of the Yangtze River and the lake, and how modifications to the Yangtze River basin and local catchment affect the hydrological and hydrodynamic conditions of the lake [26][27][28][29][30][31][32][34][35][36][37]39]. Previous studies showed that the drainage effect of the Yangtze River was the primary causal factor for the persistent dryness of Poyang Lake [37,39]. ...
Article
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Poyang lake floodplains are hydrologically complex and dynamic systems which exhibit dramatic intra-annual wetting and drying. The flow regime of the Yangtze River was previously known to play an important role in affecting Poyang Lake and its extremely productive floodplains (river–lake relationship). The recent severe declines and recessions in the lake are closely linked to the changed river–lake relationship, resulting in significant hydrological, ecological, and economic problems. This study aims to examine the spatiotemporal heterogeneity of the floodplain hydrodynamic behaviors with respect to impacts of the changed river–lake relationship, characterized by the lake water level, inundation area, and inundation duration based on a floodplain hydrodynamic model of Poyang Lake, and to further quantify the severity of dryness recently endured since 2000. Simulation results show that, in general, the current modified river–lake relationship is more likely to affect the hydrological seasonality of the floodplain system since 2000, relative to the flooding and drying cycles during past decades (1953–2000). The present hydrodynamic behaviors suffered significant change due to the greatest interference from the altered river–lake relationship, particularly for the falling period in October. On average, the floodplain water level and inundation duration decreased by 6 m and 12 days during October, respectively. Additionally, the highest monthly shrinkage rate in floodplain inundation shifted from the period of October–November to September–October, with the mean inundation area decreasing by around 50%, demonstrating an advanced and prolonged dry condition. The spatial responses of the hydrodynamics in the low-slope floodplains are most likely to be affected by the dynamic river–lake relationship, as expected. This study assessed the effects of the altered river–lake relationship on the hydrological regime of the Poyang Lake floodplains in terms of spatiotemporal distributions and changing processes for the periodic inundated behavior, which can support the relevant study of the subsequent ecological effects on the wetlands.
... In recent years, the evolution of the relationship between the Yangtze River and Poyang Lake has been increasingly affected by global climate change and human activities. At present, Poyang Lake is confronted with many challenges, such as prolonged dry season, excessively low water level, shortage of water resources, reduced water environment capacity, and ecological degradation of wetland [2]. These challenges have affected the water and ecological security, severely restricted the surrounding economic and social development, and been extensively concerned by the society. ...
... In particular, the impact of Three Gorges Reservoir (TGR) impoundment on the hydrological situation of the Yangtze River and its connected lakes has been studied intensively [1]. For example, Guo et al quantitatively studied the impact of the operation of TGR and climate change on the interaction between Yangtze River and Poyang Lake, and found that TGR has not changed the basic characteristics of the Yangtze River and Poyang Lake [2]. Zou et al [3] built the matured forecasting model to conduct a return calculation on the flood process in middle-late July in the upper reach of Yangtze River watershed. ...
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The operation of Three Gorges Reservoir (TGR) has changed the hydrological situation of Yangtze River and its connected lakes. Based on the hydrodynamic model, the influence of TGR operation from 2009 to 2014 on the Poyang Lake has been evaluated. It is found that TGR impoundment reduced the discharge of the Yangtze River and the water level of Poyang Lake, brought the decreasing of the backflow phenomenon. Especially in October, the discharge and water level of Hukou station (HKS) decreased by 9.6% and 1.09 m respectively, and this effect could be up to the Kangshan area. Meanwhile, TGR operation has also increased the water level of HKS by 0.1~0.56 m from December to May, which only affected the vicinity of Duchang. In addition, TGR operation also increased the maximum water level of HKS from April to June by 0.1~0.34 m, and that from July to August decreased by 0.22~0.4 m which is beneficial to reducing the flood control risk of Poyang Lake. But TGR impoundment changed the water exchange process between Yangtze River and Poyang Lake, and advanced the dry season, which had a certain impact on the water supply and ecological environment of the lake area.
... Zhang et al. [11] analyzed the spatial and temporal distribution of drought in Poyang Lake, exploring the influence of river-lake interaction with water impounding of the Three Gorges Dam. Guo et al. [12] quantified and evaluated the effects of the Three Gorges Dam operation and climate change on drought potential in Poyang Lake. Zhai et al. [13] found that the water conservancy projects largely aggravated the droughts in Dongting Lake, as the frequency of droughts increased by 6.81% following the construction of the Three Gorges Dam. ...
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Due to the joint influence of climate change and human activities, the hydrological rhythm of Poyang Lake has changed in recent years, leading to an increasingly severe drought problem during autumn and winter in this region. Notably, the extreme drought that occurred in 2022 had profound impacts on shipping, water supply and the ecological environment of the wetlands in the Poyang Lake Delta, sparking widespread concern. Based on the historical hydrometeorological data of Poyang Lake, we used statistical models (such as Chow test, correlation analysis, etc.) to analyze the cause of the extreme drought in the Poyang Lake Delta from the perspectives of natural factors and human activity. Through correlation analysis, we found that the water level, discharge, and drought duration of the Poyang Lake Delta were all significantly affected by climate change, particularly rainfall in the Poyang Lake basin. Furthermore, combining the results of Chow test and correlation analysis, we also found that the operation of the Three Gorges Reservoir had a notable impact on the water level of the Poyang Lake Delta. Based on remote sensing images, ecological and environmental sampling monitoring, the damage inflicted by the extreme drought event on the Poyang Lake Delta was analyzed. The results show that the inundated area of the delta wetlands in the extreme-drought year (2022) decreased by 45.75% compared with that in a normal year (2017). In addition, the ecological environment of the wetlands deteriorated significantly. The water quality parameters (TN, TP, NH4⁺-N) increased by 50.2%, 240% and 64.7%, respectively. The concentrations of TN and TP were 3.8 mg/L and 0.17 mg/L, respectively, while the context values in the delta were 1.2 mg/L and 0.075 mg/L. The density and biomass of algae increased by 87.2% and 557.9%, respectively. In contrast, the density and biomass of benthos decreased by 59.9% and 78.5%, respectively. The control strategy for the Poyang Lake Delta under extreme drought was studied through an experiment on the operation of hydraulic controllers. The results show that under extreme drought conditions, the newly built hydraulic controllers could raise the water level of the delta from 9.1 ± 0.7 m to 14.2 ± 1.8 m, thus effectively solving the water cut-off problem in the four branches of the delta. Furthermore, by adjusting the distributive ratio of the main, north, middle and south branches of the delta to 50%, 4%, 24% and 22% through newly built hydraulic controllers, the water area can be increased by 56%.
... Previous studies have revealed that the rising period of lake water level from April to June is mainly controlled by the catchment inflow, while the recession period from July to September is mainly affected by the stage of the Yangtze River. Both the forces significantly weakened from October to March in next year, but relatively the effect of the Yangtze River is stronger during October-November, and the Poyang Lake is stronger in the next months (Hu et al., 2007;Guo et al., 2011;Zhang et al., 2014). ...
... It increases from January to June, reaches the peak in June to August, and then decreases from August to December. In recent years, the influence of the watershed-controlled water conservancy projects on the river-lake interaction has become more obvious (Guo et al., 2011;Ou et al., 2011;Bing et al., 2017). ...
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The Three Gorges Reservoir (TGR) operation has profoundly altered the hydrological regimes and ecosystem in the middle and lower Yangtze River basin. Its impacts on the river flow regime, sedimentation, lake level decline, and biodiversity have been extensively studied. However, the quantitative influence of the TGR on the downstream water exchange between the Yangtze River and Poyang Lake is lacking attention. In this study, we developed a machine learning model to investigate the river–lake water exchange variations under the TGR operation in typical hydrological years, compared with the natural scenario (i.e., no TGR). The results show that the machine learning model could provide a fast and accurate approach to identify the long-distance impact of reservoirs. The operation of the TGR has significant effects on the water exchange between the Yangtze River and Poyang Lake in the impounding period, with a 10,000 m³/s decrease in reservoir discharge approximately causing a 4,000 m³/s decrease in river–lake water exchange in the dry year and a decrease of 6,000 m³/s and 8,000 m³/s in reservoir discharge causing an increase of 4,000 m³/s and 6,000 m³/s in the normal year and the wet year, respectively. The TGR effect varies with different hydrological conditions of the river and lake, showing longer time range (from May to October) and greater degree (1.5 times the change rate in other years) in the wet year. The TGR operation is beneficial to the water maintenance of the lake in the dry year and flood control in the lake area in the wet year. This study provides a constructive approach and valuable information for decision making in water resource management and ecosystem protection in large river–lake systems.
... Poyang Lake is a typical river-connecting lake in the middle reaches of the Yangtze River. Due to the different seasonal variation characteristics of precipitation in the middle and upper reaches of the Yangtze River and the Poyang Lake basin, the intensity of water exchange between the Yangtze River and Poyang Lake varies with the seasons, and the two affect each other, leading to seasonal changes in the water level and discharge of the river and lake [21]. When the water levels of both the river and the lake are high, the flood probability of Poyang Lake increases, and the seasonal lakes are connected to the main lake. ...
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Poyang Lake is the largest freshwater lake in China, an internationally important wetland and the largest migratory bird habitat in Asia. There are numerous seasonal lakes in the Poyang Lake region, and these lakes create a complex and diverse wetland landscape and serve as the main activity area for migratory birds. Seasonal lakes have significant effects on hydrological and ecological processes and are highly susceptible to various changes, but research on seasonal lakes is relatively limited. Based on long-term remote sensing images, this study analyzed the spatiotemporal variation characteristics of seasonal lakes and their influencing factors and ecological effects. The conclusions were as follows: the average water area of seasonal lakes showed a unimodal change during the year, reaching a maximum in July and a minimum in January. The interannual water area fluctuated greatly, and the overall water area showed a small downward trend. In terms of spatial variation, the seasonal lakes were connected with the main lake in the wet season and separated from the main lake in the dry season. Among the natural factors, the influences of temperature, evaporation, and rainfall on the water area of the seasonal lakes were successively reduced. In addition, the incoming water from the Yangtze River had an important influence. Among the human factors, the traditional fishing method “enclosing sublakes in autumn” had the greatest impact on the water area in a specific period, followed by the indirect impact of the Three Gorges Project.
... The precipitation amount decreases after July. However, the water level of the Yangtze River rises due to the water supply from precipitation and snowmelt in its upper reaches, which feeds the Poyang Lake and makes the water level of this Poyang Lake continue to rise [53] under the continuous influence of human activities and the Yangtze River water diversion and a large amount of sediment deposits, which has an important influence on the area of Poyang Lake. Figure 1 shows the river networks in the Poyang Lake basin. Since most of the water bodies in the Poyang Lake basin are distributed in the northern region, we have selected an area of interest to compare the water identification effects of different methods. ...
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The accurate acquisition of water information from remote sensing images has become important in water resources monitoring and protections, and flooding disaster assessment. However, there are significant limitations in the traditionally used index for water body identification. In this study, we have proposed a deep convolutional neural network (CNN), based on the multidimensional densely connected convolutional neural network (DenseNet), for identifying water in the Poyang Lake area. The results from DenseNet were compared with the classical convolutional neural networks (CNNs): ResNet, VGG, SegNet and DeepLab v3+, and also compared with the Normalized Difference Water Index (NDWI). Results have indicated that CNNs are superior to the water index method. Among the five CNNs, the proposed DenseNet requires the shortest training time for model convergence, besides DeepLab v3+. The identification accuracies are evaluated through several error metrics. It is shown that the DenseNet performs much better than the other CNNs and the NDWI method considering the precision of identification results; among those, the NDWI performance is by far the poorest. It is suggested that the DenseNet is much better in distinguishing water from clouds and mountain shadows than other CNNs.
... About the inconsistency characteristics of Poyang Lake, the study mainly focused on the the influence of the change in the hydrological regime at the main stream of the Yangtze River to the hydrological regime of Poyang Lake. Based on the data analysis from 2004 to 2008, Guo Hua et al [4] concluded that the large amount of water storage in the Three Gorges Reservoir in October, resulting in the decrease of the discharge of the Yangtze River, which significantly weakens the influence of the Yangtze River on the water level of Poyang Lake. The coupled hydrodynamic model of rivers and lakes in the middle steam of the Yangtze River was used by Wang Yingchun et al [5], and the results shown that the water level of Duchang Station in Poyang Lake will be reduced by 0.09-1.11 ...
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